Nasa can now forecast sinkholes

But probably couldn't have saved the Corvettes in Bowling Green, Kentucky.

Two years ago, a giant sinkhole swallowed trees whole in a Louisiana bayou. This year, Nasa says it could have predicted it.

It might sound like too little too late, but with five-to-ten times more sinkholes occurring in this country because of the wet weather this year, any potential tool for mapping precarious landmasses will be most welcome.

The sinkhole Nasa is basing its study on, near Bayou Corne, was a monster measuring 10.1 hectares. It was 229m (751ft) deep by the time it ceased swallowing everything in sight. In a paper published in the journal Geology, Cathleen Jones and Ron Blom, from the Jet Propulsion Laboratory, have shown how radar data captured by Nasa's Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR) between 2011 and 2012 could have been used to predict the natural catastrophe.

The UAVSAR captures interferometric synthetic aperture radar (InSAR) data—the returning waves the aircraft captures are used to generate digital surface elevation and deformation maps. It's the same technique used to assess fault lines, or even glaciers, capturing incremental changes at the centimeter scale over the course of years.

Although it would seem impossible to predict sinkholes, which happen so suddenly (at least the cover-collapse kind), the groundwork that causes them is being laid over some time. They can occur when rainwater and all the acids it carries permeate the soil to reach soluble rockbeds that are vulnerable, often made from limestone, gypsum, or salts. Over time, chunks begin to erode to create holes and break the connections between the layers. Loose soil layers from above then fill those gaps to create an unstable replacement. Eventually, when these holes and gaps grow too great, this "cover" of soil will collapse. In the case of Bayou Corne, there was also an existing hole to contend with—an underground storage space 914m (2,998ft) below the surface connected to a well—and often sinkholes occur when a natural underground cave already exists.

Those loose soil particles trickling down to the earth below to fill the gaps before the collapse, however, could be a possible sign of danger. And this is essentially what the radar captured—incremental movements in soil particles that over time represent an indicative shift.

The data showed that the surface layer moved 26cm horizontally a month before the collapse, in the direction where the collapse was to occur. These movements were happening in a larger area, stretching around the sinkhole to 500m × 500m.

Although the sinkhole occurred in August 2012, data showed the deformation was still growing in October 2012 and could potentially start inching too close to another underground storage zone.

"While horizontal surface deformations had not previously been considered a signature of sinkholes, the new study shows they can precede sinkhole formation well in advance," said Jones. "This kind of movement may be more common than previously thought, particularly in areas with loose soil near the surface… At Bayou Corne, it appears that material is continuing to flow into the huge cavern that is undergoing collapse."

The authors conclude in Geology: "This work suggests that InSAR data collected operationally for hazard monitoring could, in some cases, identify sinkhole development before surface collapse and decrease subsequent danger to people and property."

It's a big "could," though. Plenty of other factors come into play with any sinkhole. The large salt dome that sits below the surface at the bayou was being used by companies to store gases and make salt water for local factories, and a class-action lawsuit has since been filed against two of those, Texas Brine and Occidental Chemical. For preventative measures, it might be better to keep a closer eye on manmade practices.

But still, the localized groundshift in the months prior to the collapse do present interesting possibilities for future monitoring. It seems to make sense to monitor regions where natural or manmade underground caves pose a threat.

Coauthor Blom admits: "Our discovery at Bayou Corne was really serendipitous. But it does demonstrate one of the expected benefits of an InSAR satellite that would image wide areas frequently."

Alas, the article doesn't explain that this method wouldn't have worked for finding sinkholes under buildings, since the presence of the building makes it impossible to see the movement of the ground under it.

There are sink holes appearing all over the UK too, swallowing people's cars and cracking their houses and such. The scale is much smaller. I can't help but wonder if its related to the new technique of fracking where explosions are rigged up underground to release natural gasses upwards for collection. What exactly happens to the cavities and caverns deep underground after the gasses have gone... and water finds its way into them... could well be sink holes, if you ask me.

There are sink holes appearing all over the UK too, swallowing people's cars and cracking their houses and such. The scale is much smaller. I can't help but wonder if its related to the new technique of fracking where explosions are rigged up underground to release natural gasses upwards for collection. What exactly happens to the cavities and caverns deep underground after the gasses have gone... and water finds its way into them... could well be sink holes, if you ask me.

It seems like fracking might be connected to some earthquakes, but it is probably far too deep to create sink holes. Fracking is usually done at incredible depths, 5000 to 20,000 feet deep, far, far deeper than sinkholes would be. I suspect 4000-19,000 feet of intervening rock is plenty to support the surface.

incredible depths ? deep, impressive, lot of hard work to do it yes , incredible no

Not after fracking its not solid rock and not everything immediately under the surface is solid rock.

Give it 20 -200 years before writing off the idea that fracking can't/doesn't cause sinkholes

There are sink holes appearing all over the UK too, swallowing people's cars and cracking their houses and such. The scale is much smaller. I can't help but wonder if its related to the new technique of fracking where explosions are rigged up underground to release natural gasses upwards for collection. What exactly happens to the cavities and caverns deep underground after the gasses have gone... and water finds its way into them... could well be sink holes, if you ask me.

Not really. The sinkholes happen in areas where there have always been sinkholes, which is uncorrelated wtih the areas where fracking is done.

There are sink holes appearing all over the UK too, swallowing people's cars and cracking their houses and such. The scale is much smaller. I can't help but wonder if its related to the new technique of fracking where explosions are rigged up underground to release natural gasses upwards for collection. What exactly happens to the cavities and caverns deep underground after the gasses have gone... and water finds its way into them... could well be sink holes, if you ask me.

It seems like fracking might be connected to some earthquakes, but it is probably far too deep to create sink holes. Fracking is usually done at incredible depths, 5000 to 20,000 feet deep, far, far deeper than sinkholes would be. I suspect 4000-19,000 feet of intervening rock is plenty to support the surface.

incredible depths ? deep, impressive, lot of hard work to do it yes , incredible no

Not after fracking its not solid rock and not everything immediately under the surface is solid rock.

Give it 20 -200 years before writing off the idea that fracking can't/doesn't cause sinkholes

Two years ago, a giant sinkhole swallowed trees whole in a Louisiana bayou. This year, Nasa says it could have predicted it.

I'll go one better. I can predict it within an hour after it happens - no need to wait a full year afterwards!

Jokes aside, this is a potentially useful observation. I think the trick will be catching sight of the signs of impending collapse within the sea of raw data in a timely manner.

I suspect this to be one of the unquestionably valuable uses of big data. At least, -I- would rather see it used to pick up these needle in the haystacks of impending disasters rather than used for more successful marketing.

Why not use the same technology the oil industry used to map subsurface geology and archeologists use to discover buried cities to map where there are trouble spots that could affect structures in sinkhole-prone areas?

There are sink holes appearing all over the UK too, swallowing people's cars and cracking their houses and such. The scale is much smaller. I can't help but wonder if its related to the new technique of fracking where explosions are rigged up underground to release natural gasses upwards for collection. What exactly happens to the cavities and caverns deep underground after the gasses have gone... and water finds its way into them... could well be sink holes, if you ask me.

Yes, Franking must be the answer, even though it hasn't actually started to any meaningful degree in the UK yet.

Because those people know the Corvette reference and are displeased that you do not. I would also venture to guess that they are unhappy that you would rather encourage better journalism than to simply Google it for yourself.

Interesting article and great stuff coming from NASA and JPL as usual. But the photo without caption is one of the "Wink Sink" events occurring in Texas, yet the article spends a good deal of time talking about the Bayou Corne Sinkhole in Louisiana, which it describes as a "natural catastrophe". It would have been nice to have some link or photo, or even the slightest background description of that event for those of us who apparently live under rocks.

It would have been even nicer to know that the Bayou Corne event is not exactly a natural catastrophe, but rather "A massive oil and gas disaster you've probably never heard of". The well under this sinkhole is owned by Occidental Petroleum and is operated by the Texas Brine drilling company.

"On August 3, Louisiana Gov. Bobby Jindal declared a statewide emergency, and local officials in Assumption ordered the mandatory evacuation of about 300 residents of more than 150 homes located about a half-mile from the sinkhole. Four months later, officials continue to tell residents that they do not know when they will be able to return home. A few have chosen to ignore the order and have stayed in their homes, but the neighborhood is now quiet and nearly vacant. Across the road from the residential community, a parking lot near a small boat launch ramp has been converted to a command post for state police and emergency responders.

This place is no longer fit for human habitation, and will forever be," shouted one frustrated evacuee at a recent community meeting in Assumption.

The Bayou Corne sinkhole is an unprecedented environmental disaster. Geologists say they have never dealt with anything quite like it before, but the sinkhole has made few headlines beyond the local media. No news may be good news for Texas Brine, a Houston-based drilling and storage firm that for years milked an underground salt cavern on the edge of large salt formation deep below the sinkhole area. From oil and gas drilling, to making chloride and other chemicals needed for plastics and chemical processing, the salty brine produced by such wells is the lifeblood of the petrochemical industry."

...

Credit to the good work being done at NASA and JPL. I would have read the Geology paper, but it requires a paid subscription.